In the quest for high strength structural materials having superior mechanical properties, such as high tensile strength and elongation, it has recently been discovered that such materials could be achieved by the preparation of structured polymeric networks derived from liquid crystalline precursors.
Recent discoveries in this field involve the use of liquid crystalline diglycidyl compounds and diisocyanate compounds in the preparation of structured networks. Such networks have been prepared utilizing polymerization, polyaddition, and polycondensation processes, as disclosed in the U.S. Pat. Nos. 4,762,901, issued Aug. 9, 1988, and 4,764,581, issued Aug. 16, 1988, to H. P. Muller et al. Such processes were accomplished during the mesophase temperature range of the liquid crystalline, polyfunctional unit.
Other recent work has involved the polymerization of diacrylate Schiff bases from the nematic state utilizing a magnetic field to orient the cross-linked network, as reported in the literature by B. S. Clough, A. Blumstein, and E. C. Hsu, Macromolecules, 9(1), 123, 1976.
The present invention seeks to prepare high mechanical strength cross-liked network structures from a new class of liquid crystalline dicyanate compounds. The invention has synthesized optionally ring substituted di-(4-hydroxyphenyl) terephthalate as a precursor in the preparation of highly structured triazine thermosetting networks. The orientation of the triazine networks has been accomplished by magnetically aligning the liquid crystalline phase of the precursor during the curing reaction.
The triazine thermosets of this invention have a number of advantages over the well known epoxy matrices. Reaction conversions of the triazine are nearly one hundred percent, resulting in few, if any, unreacted end groups. In addition, there are no secondary reactive groups produced during the course of the reaction. By contrast, the epoxy chemistries produce alcohols, whose volatility is undesirable, and present a production hazard.
It is also contemplated by the current invention to use the newly synthesized dicyanate ester precursors in admixture with other well known resins, such as the aforementioned epoxies and acrylates, to form new, high strength materials.